Sounds like the vodka would be the best bet. I'd rather have residual vodka than antifreeze. Even if it's NSF safe. The taste can't be good... I'll have to see where a few liters of bottom shelf will get me. Thanks for the idea.

As far as the system goes, here's a few picks to get an idea.

Heat exchanger

From the top view of the heat exchanger, the long horizontal pipes at the very bottom cracked about half way. So I cut those out near the crack and put in a union to a new pipe. I also found some brass elbows with drain screws and installed on the left side of the tubes. I pitched the tubes so I can get most of the water out with the drain. These drains will hopefully also help in removing air when I'm initially filling the system (dry pumps don't work well).

Brass elbows

We will see when the weather warms back up to the high 50's here in sunny denver next week!